$ cat data
2007/02/19 00:00:06: Information: Switch SDT for out stream 510
2007/02/18 00:00:06: Information: Switch SDT for out stream 510
2007/02/19 01:00:00: Information: Switch SDT for out stream 510
2007/02/18 01:00:00: Information: Switch SDT for out stream 510
2007/02/19 01:59:00: Information: Switch SDT for out stream 510
2007/02/18 01:59:00: Information: Switch SDT for out stream 510
$
$
$ cat script
#! /usr/bin/ksh


timetosecs()
{
        typeset time h m s
        time=$1
        time=${time%:}
        h=${time%%:*}
        time=${time#${h}:}
        m=${time%:*}
        s=${time#*:}
        h=${h#0}
        m=${m#0}
        s=${s#0}

        echo $((h*3600+m*60+s))
}

#clear
echo  "Please enter word to search for : \c"
read searchstring
echo  "Please enter outstream to search for : \c"
read outstream
echo  "Switch or Build : \c"
read switchorread
echo  "Please enter search date : (yyyy/mm/dd) \c"
read searchdate
echo  "Please enter start time : (hh:mm:ss) \c"
read starttime
startsecs=$(timetosecs $starttime)
echo  "Please enter end time : (hh:mm:ss) \c"
read endtime
endsecs=$(timetosecs $endtime)

exec < $outstream
while read date time rest ; do
        [[ $date != $searchdate ]] && continue
        secs=$(timetosecs $time)
        ((secs<startsecs)) && continue
        ((secs>endsecs)) && continue
        echo $date $time $rest
done
$
$
$ ./script
Please enter word to search for : sjsjs
Please enter outstream to search for : data
Switch or Build : sjsjs
Please enter search date : (yyyy/mm/dd) 2007/02/19
Please enter start time : (hh:mm:ss) 01:00:00
Please enter end time : (hh:mm:ss) 02:00:00
2007/02/19 01:00:00: Information: Switch SDT for out stream 510
2007/02/19 01:59:00: Information: Switch SDT for out stream 510
$